Add initial link cable clock sync

1 files changed, 29 insertions, 0 deletions

diff --git a/src/sequencer.c b/src/sequencer.c
index 867e686..7c989f2 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -20,6 +20,19 @@ bool redraw_piano_note = true;
 bool update_bpm = false;
 
 void
+gate_off(void) {
+    SIO_MODE = SIO_MODE_GP
+        | SIO_SC_OUT(1)
+        | SIO_SD_OUT(1)
+        | SIO_SI_OUT(0)
+        | SIO_SO_OUT(1)
+        | SIO_SC(0)
+        | SIO_SD(1)
+        | SIO_SO(0);
+    TIMER_CTRL_1 = 0;
+}
+
+void
 play_step(void) {
     Pattern *pat = &patterns[current_pattern];
     if (current_pattern != next_pattern && step_counter == 15) {
@@ -135,6 +148,22 @@ play_step(void) {
         SOUND_NOISE_CTRL = 0;
         SOUND_NOISE_FREQ = 0;
     }
+    // TODO: This should be configurable e.g. po needs a 1 each 2 to sync
+    // exactly, but we can also just want a pseudo clock divider.
+    if (step_counter % 2 == 0) {
+        SIO_MODE = SIO_MODE_GP
+            | SIO_SC_OUT(1)
+            | SIO_SD_OUT(1)
+            | SIO_SI_OUT(0)
+            | SIO_SO_OUT(1)
+            | SIO_SC(1)
+            | SIO_SD(1)
+            | SIO_SO(0);
+        int n_ticks = -244181 / 600;
+        irs_set(IRQ_TIMER_1, gate_off);
+        TIMER_DATA_1 = n_ticks;
+        TIMER_CTRL_1 = TIMER_CTRL_IRQ | TIMER_CTRL_ENABLE | TIMER_CTRL_FREQ_3;
+    }
     step_counter = (step_counter + 1) % 16;
     redraw_piano_note = true;
 }